A semiconductor manufacturing process includes a series of processes of arranging a plurality of chips on a silicon wafer and packaging and cutting the resulting structure into separate chips. In order to package and cut the resulting structure into a plurality of chips, a process of applying an electrical signal to the respective chips to check whether or not the respective chips operate normally must be performed. This process is called a semiconductor inspection process. The semiconductor inspection process is performed using a probe card having a contact member corresponding to a chip formed on the silicon wafer. The contact member is brought into contact with the chip on the silicon wafer and the electrical signal is applied thereto to check whether or not the chip operates normally. This contact member is hereinafter referred to as a probe.
The semiconductor inspection process includes operations of disposing a desired silicon wafer on a wafer chuck, bringing a probe tip into contact with a desired pad on the silicon wafer, and performing a desired inspection by applying the electrical signal to the desired pad while pressing the probe tip with a predetermined physical force.
At this time, a sufficient over drive (OD) must be applied in order to bring all the probe tips of the probe card into contact with the desired pads of the silicon wafer. Also, the sufficient OD must be constantly maintained in order to prevent the fatal damage of the pads. This requires means for sensing the current state of the OD in real time.
Also, a constant planarity of the silicon wafer disposed on the wafer chuck must be always maintained in order to bring the probe tips into precise contact with the corresponding pads and to prevent the damage of the pads. Therefore, it is required to develop means for accurately sensing the planarity of the silicon wafer in real time.